Line four 8-inch round cake pans (if you have four--otherwise you can use 2 or 3, let the layers freeze completely, then remove from the pans, continue to freeze, and repeat for the remaining layers) with plastic wrap, leaving a few inches of overhang around the edges.
Remove all 3 tubs of ice cream from the freezer, and let sit to soften, about 10 minutes. In the meantime, slice the jelly-rolls.
Starting with the bubble-gum ice cream, transfer the soften ice cream to one of the lined cake pans and gently press the broken waffle cones and chopped drumsticks (if using) into the layer. Place in the freezer.
Next, transfer 1/2 of the vanilla bean ice cream into another of the lined cake pans, and stir in 1/2 of the strawberry jelly/preserves and a few squirts of the strawberry syrup to swirl. Break apart the Pop-Tarts and gently press across the ice cream. Return to freezer.
Transfer the remaining vanilla bean ice cream into the third cake pan, add the remaining jam, more strawberry syrup, then stir and swirl. Crumble the oatmeal cookies onto to the top of the layer and freeze.
Lastly, stir the strawberry ice cream until smooth and transfer to the last cake pan. Gently push the sliced jelly rolls into the ice cream and freeze.
Remove the bubble-gum/waffle-cone ice cream layer from the freezer and use the plastic wrap overhang to remove the layer from the pan. Peel off the plastic wrap, and place the layer on a plate or cake board. Next, remove the swirled-vanilla with Pop-Tarts layer and repeat the steps above.
Repeat with the strawberry ice cream/jelly-roll layer. Finally, remove the vanilla-bean/oatmeal cookie layer from the freezer and from the pan, and then invert the layer, oatmeal-cookie-side down and place on top of the cake. Cover the entire cake in plastic wrap, wiggle into place if necessary, and return to the freezer for at least 4-6 hours (ideally overnight) to set.
Place a stainless stand mixer bowl and the whisk attachment (or if using a hand mixer, a stainless mixing bowl and the mixer beaters) in the freezer for at least 20 minutes.
Into a small microwave-safe bowl, sprinkle the gelatin onto the water and let sit for 10 minutes. Microwave the mixture for 20 seconds and stir to combine.
Remove the bowl and whisk from the freezer, add the cream and sugar to the bowl and whip on medium speed for 30 seconds. With the mixer running, add the gelatin mixture in one go and a drop or two of pink food gel coloring. Increase the speed to medium-high and whip until medium-stiff peaks form (thick enough to spread/pipe/hold its shape, but not over-whipped and grainy), but watch closely! This only takes about 1 minute or so.
Remove the chilled cake from the freezer and remove the plastic wrap.
Frost the cake with the pink whipped cream, just as you would a regular cake--use a small offset palette knife to cover the top of the cake, and a medium straight palette knife to frost the sides. Working quickly, gently press the sprinkles along the bottom third perimeter of the cake. Cover the remaining frosting with plastic wrap and chill. Return the cake to the freezer for about an hour.
Remove the pink frosting from the fridge and transfer to a piping bag fitted with a large plain round tip. Remove the cake from the freezer and pipe a pink poofs around the top of the cake. Gently press sprinkles into the bottom third of the cake, and add a few on top, if desired. The cake will keep up to 1 week in the freezer.